Automatic starter for electric motors



PATENTED FEB. 16, 1904.

W. G. OBRIEN.

AUTOMATIC STARTER FOR ELECTRIC MOTORS.

APPLICATION FILED MAY L 1903.

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THE Nomus varzas co. PHOYCLLIYHD. WASHINGYON, DV 0.

UNITED STATES Patented February 16, 1904;.

. WILLIAM C. OBRIEN, OF BALTIMORE, MARYLAND.

AUTOMATIC STARTER FOR ELECTRIC MOTORS.

SPECIFICATION forming part of Letters Patent No. 752,097, dated February 16, 1904:.

Application filed May 4:, 1903. Serial No. 155.589. (N model.)

To all whom it may concern:

Be it known that I, WILLIAM C. OBRIEN, a citizen of the United States, residing at Baltimore, in the State of Maryland, have invented certain new and useful Improvements in Automatic Starters for Electric Motors, of which the following is a specification.

My invention comprises improvements in automatic starting devices for direct-current electric motors; and it includes a solenoid or electromagnetic controlling device arranged in an independent circuit and adapted to operate the arm or brush which cuts the resistance out of the armature-circuit, means for interrupting the solenoid-circuit after the motor has been started, and'means for holding the contact arm or brush in position with the resistance out of circuit until the main switch is opened to stop themotor.

In the accompanying drawings, Figure 1 represents in side view my improved automatic motor-starting device, and Figs. 2 and 3 are similar detail views showing modified forms of circuit-breakers.

Referring to Fig. 1 of the drawings, 1 and 2 indicate the supply wires or mains through which the current is carried to the bindingposts 3 and 1, respectively, of the motor-starting device,and 5 indicates a double-pole switch for opening and closing the circuit through the mains 1 and 2. The main 2 is connected by a wire 6 to a binding-post F, and a wire 7 leads from said binding-post to the field and armature circuits of the motor which is to be operated. The field-circuit of the motor is connected to the main 1 by a wire 8, leading to a binding-post F, and a wire 9, leading from the binding-post F to the post 3, said circuit including the coils of an electromagnet B. The armature-circuit of the motor is connected by a wire 10 to a binding-post A, and the latter is connected by a wire 11 to an upper terminal-plate 12 of a series of contact plates or surfaces (J, which latter are connected to a series of resistance-coils R in the usual manner. From the contact-plates C the armature-circuit extends through a brush 13, a pivoted contact arm or lever 14, and a wire 15, to the binding-post 3. For the purpose of preventing the interruption of the armaturecircuit in case the contact-arm 14 is accidentally moved away from the contact-plates I connect the lower terminal contact-plate 16 with the binding-post 3 by a wire 17, so that the current will flow through the entire resistance to the armature in case the contact arm and brush 13 are moved away from the contact-plates. The contact-lever 14: is automatically moved upward to cut resistance out of the armature-circuit by a solenoid 18, which is included in a circuit independent of the motor-circuits, and the upward movement of the contact-arm is retarded by a suitable retarding device D, which may be a train of gears, as indicated in the drawings, or a dash-pot arranged to retard the upward movement of the lever and permit its free downward move ment. The solenoid-core 19, as shown, is connected to the contact-lever by a link 20. The solenoid-circuit extends from the binding-post A through a conductor 21 to the coil of the solenoid, thence by a conductor 22 to a contact-plate 23, arranged in the path of a brush 24 upon the lever 14, thence through said brush and lever to the conductor 15, which connects the lever with the bindingpost 3. The contactplate 23, as shown, is arranged parallel with the central and. lower portions of the series of resistance-contacts C; but it does not extend upwardly as far as the series of resistance-contacts extend. The contact-plate 23 is connected by a conductor 25 with a metal stop-pin or tripping device 26, which latter. is arranged in the path of a circuit-breaking device E, consisting of abell-crank lever pivoted to the contact-lever 1 1 andhaving arms 27 and 28, substantially at right angles to one another. As shown, the arm 28 carries a weight 29, which causes the arm 27 to normally stand in a horizontal position, as indicated in dotted lines in the lower part of Fig. 1. The stop-pin 26 is arranged in substantially the same radial line as the top of the strip 23 and in such position that the arm 27 will engage the stop before the brush 21 leaves the strip 23. The solenoidcircuit is thus continued after the parts 23 and 21 separate, and no spark occurs between said parts. In operation when the circuit is closed by the switch 5, the contact lever 14 being then in its lowermost position, (indicated in dotted lines,) the circuit through the solenoid capacity during that time.

is completed through the strip 23 and brush 24. The solenoid is thus energized and draws the lever upward against the action of the re tarding device I) until the iron armature b at the rear end of the lever comes within the influence of the magnet B, which is included in the field-circuit and arranged in position to hold the contact-lever stationary when the latter has been moved to cut out all of the armature resistance. As the lever approaches the upward limit of its movement the solenoid-circuit is completed by the engagement of the arm 27 with the post 26 before the brush 24: leaves the strip 23. As the arm 27 of the bell-crank lever is arrested by the stop 26, through which the solenoid-circuit is completed, the continued upward movement of the contact-lever causes the bell-crank lever to tilt about its axis, as shown in full lines in the drawings, and when the contact lever reaches the last elongated contact-strip 12 and the opposite end of the lever is in close proximity to the holding-magnet B the arm 27 of the bell-crank lever passes the stop 26 and the weight 29 causes said arm to move rapidly away from the stop 26 and to swing into the position shown in dotted lines in the upper part of the drawings, thus causing a wide and rapid separation of the parts 26 and 27, which prevents the continuation of an are between said parts. hen the contact-lever reaches the uppermost position, (indicated in dotted lines,) the solenoid is deenergized by the interruption of its circuit; but the lever is maintained in this position by the holding-magnet B. When the switch 5 is opened to stop the motor, the holding-magnet becomes deenergized and the parts drop to their normal positions.

As the electromagnetic controlling device which operates the contact-lever and which is preferably a solenoid, as shown in the drawings, is in a circuit independent of the motorcircuits, the size and number of turns of wire in the solenoid-coil have no relation to the motor-conductors, and as the solenoid-circuit is deenergized as soon as the resistance is cut out of the armature-circuit the solenoid-coil may have any desired size and number of turns of wire to effect a strong pull upon the solenoid-core. Thus, for instance, the solenoid-coil instead of being wound with a great length of fine wire may be wound with fewer turns of comparatively coarse wire at much less expense, and as the coil is only in circuit for a very short time it may be made to carry a current in excess of its normal safe carrying This may be done where it is desired to obtain a maximum amount of work with a minimum amount of wire. The holding-magnet, which is in the field-circuit of the motor, requires but a small consumption of energy, as the contact-lever remains in contact with the pole-pieces of the magnet. No energy is wasted in the solenoid which is out of circuit except for the short time required to move the lever in starting.

In Fig. 2 I have shown a modification of the circuit-interrupting device consisting of a spring Gr, attached to the end. of thecontactlever 14 and adapted to maintain contact with the post 26 until the lever 1 1 has about reached its limit of movement, when the spring passes thepost 26 and by its stored energy swings to a considerable distance away from the post, thus preventing the continuation of an are. I prefer, however, to use the weighted leverarm for breaking the circuit, as it oscillates more freely than the spring and the resistance to the movement of the lever 14 is more uniform when the weighted lever is used than when a spring is used.

Instead of placing the circuit-interrupting device upon the movable lever 14 it may be placed upon a fixed support adjacent to said lever and so arranged as to be tripped thereby just before the completion of the movement of the lever. Such an arrangement is shown in Fig. 3, wherein a bell-crank lever E is pivoted upon a fixed stud 30, which latter is connected to the conductor 25, leading to the contact-strip 23. The contact-arm 27 of the bell-crank lever is arranged in the path of an extension 31 upon the lever 14;, being normally held in the horizontal position by the weight 29 upon the arm 28 of the bell-crank lever. The upward movement of the contactlever 14, it will be seen, will near the end of such movement lift the balanced contact-arm 27 and tilt it out of its normal position, and as soon as this balanced arm is released or tripped it will swing downwardly on account of the weight 29, andthus cause a wide and quick separation of the arm 27 and the end 31 of the contact-lever 14:.

Having described my invention, what I claim, and desire to secure by Letters Patent,

1. In an automatic starting device for electric motors, a resistance arranged in the armature-circuit of the motor, a series of contactsurfaces connected therewith, a contact device movable over said surfaces to increase and decrease the resistance in the armature-circuit, an electromagnetic controlling device arranged to move said contact device to cut the resistance out of the armature-circuit, an independent circuit including the coils of said controlling device,1neans for automatically interrupting said latter circuit when the resistan ce has been cut out of the armature-circuit, and electromagnetic means arranged permanently in series with the field circuit of the motor, for holding said contact device in position with the resistance out of the armaturecircuit.

2. In an automatic starting device for electric motors, aresistance arranged in the armature-circuit of the motor, aseries of contactsurfaces connected therewith, a contact device movable over said surfaces to increase. and decrease the resistance in the armature-circuit, a solenoid having a core operatively connected to said contact device and adapted, when the solenoid is energized, to move said contact device to cut the resistance out of the armaturecircuit, an independent circuit including the coils of said solenoid, meansfor automatically interrupting said latter circuit when the resistance has been cut out of the armature-circuit, and an electromagnet having its coils included permanently in series. with the fieldcircuit of the motor and arranged to hold said contact device in position with the resistance out of the armature-circuit.

3. .In an automatic starting device for electric motors, the combination with a resistance arranged in the armature-circuit of the motor, a series of contact surfaces connected with said resistance, a contact device movable over said surfaces, an electromagnetic controlling device adapted to move said contact device into position to cut the resistance out of the armature-circuit and a circuit for said electromagnetic device, of means for interrupting said latter circuit comprising an arm connected with the contact device and movable relatively thereto, and a stop arranged in the path of said arm and adapted to trip the arm, said arm and stop being electrically connected to opposite sides of the circuit of said electromagnetic controlling device.

4. In an automatic starting device for electric motors, the combination with a resistance arranged in the armature-circuit of the motor,

a series of contact surfaces connected with said resistance, a contact device movable over said surfaces, an electromagnetic controlling device adapted to move said contact device into position to cut the resistance out of the armaturecircuit and a circuit for said electromagnetic device, of means for interrupting said latter circuit comprising a balanced arm piv' otally connected to the contact device and movable therewith, and a stop arranged in the path of said arm, said arm and stop being connected to opposite sides of the circuit of the electromagnetic controlling device.

5. In an automatic starting device for electric motors, the combination with a resistance arranged in the armature-circuit of the motor, a series of contact-surfaces connected with sai'd resistance, a contact device movable over said surfaces, an electromagnetic controlling device adapted to move said contact device into position to cut the resistance out of the armature-circuit and a circuit for said electromagnetic device, of means for interrupting said latter circuit comprising a bell-crank lever pivotally connected to the contact device, said lever having a weight upon one arm, and a stop arranged in the path of the other arm of the lever, said stop andlever being connected to opposite sides of the circuit of the electromagnetic controlling device.

6. In an automatic starter for electric motors, a resistance arranged in the armaturecircuit and a series of contact-surfaces connected therewith, an electromagnetic controlling device, a contact bar or lever movable by said controlling device when the latter is energized to cut resistance out of the armature-circuit, a circuit for said controlling device including a part upon said bar and a fixed contact-strip arranged to be engaged by said bar during the first part of its movement and to be disconnected therefrom near the end of its movement, and an electromagnet in the field-circuit of the motor for holding said bar or lever with the resistance cut out of circuit.

7. In an automatic starter for electricmotors, a resistance arranged in the armaturecircuit and a series of contact-surfaces connected therewith, an electromagnetic controlling device, a contact bar or lever movable by said controlling device when the latter is energized to cut resistance out of the armaturecircuit, a circuit for said controlling device including a fixed contact-strip and a stop connected to one side of said circuit, a part upon said bar at the other. side of said circuit arranged to engage said strip during the first part of the movement of the bar and to be dis engaged therefrom near the end of said movement, a balanced contact-arm upon said bar arranged to engage said stop before the bar and contact-strip are disengaged, and to be tripped and released by said stop after said parts have become disengaged, and an electromagnet in the field-circuit of the motor for holding said bar or lever with the resistance cut out of. circuit.

8. In an automatic starting device for electric motors, the combination with a resistance arranged in the armature-circuit of the motor, a series of contact-surfaces connected with said resistance, a contact device movable over said surfaces, an electromagnetic controlling device adapted to move said contact device into position to cut the resistance out of the armature-circuit and a circuit for said electromagnetic device, of means for interrupting said latter circuit comprising a balanced contactarm arranged to be tripped by the movement of the contact device, said arm and tripping means being electrically connected to opposite sides of the circuit of said electromagnetic controlling device.

9. In an automatic starter for electric motors, a resistance arrangedin the armature-circuit and a series of contact-surfaces connected therewith, an electromagnetic controlling device, a contact bar or lever movable by said controlling device when the latter is energized to cut resistance out of the armature-circuit, a circuit for said controlling device including a part upon said bar and a fixed contact-strip arranged to be engaged by said bar during the first part of its movement and to be disconnected therefrom near the end of its movement, and electromagnetic means for holding said bar or lever with the resistance cut out of circuit.

10. In an automatic starting device for electric motors, the combination with a resistance arranged in the armature-circuit of the motor, a series of contact-surfaces connected with said resistance, a contact device movable over said surfaces, an electromagnetic controlling device adapted to move said contact device into position to cut the resistance out of the armature-circuit and a circuit for said electromagnetic device, of means for interrupting said latter circuit comprising a yielding contactarm arranged to be moved from its normal position and tripped by the operation of said controlling device, said contact-arm and tripping means being electrically connected to opposite sides of the circuit of said electromagnetic controlling device.

11. In an automatic starter for electric motors, a resistance arranged in the armature-circuit, an electromagnetic controlling device and means operated thereby for cutting resistance out of the armature-circuit, a circuit for said controlling device including a part movable by said controlling device and a fixed contactstrip arranged to be engaged by said movable part during the first portion of its movement and to be disconnected therefrom near the end of its movement, means for maintaining the continuity of said controlling-device circuit after said parts have become disengaged, and means for automatically interrupting said latter circuit when the resistance has been cut out of the armature-circuit.

12. In an automatic starter for electric motors, a resistance arranged in the armature-circuit, an electromagnetic controlling device and means operated thereby for cutting resistance out of the armature-circuit, a circuit for said controlling device including a part movable by said controlling device and a fixed contactstrip arranged to be engaged by said movable part during the first portion of its movement and to be disconnected therefrom near the end of its movement, means for maintaining the continuity of said controlling-device circuit after said parts have become disengaged, means for automatically interrupting said latter circuit when the resistance has been cut out of the armature-circuit, and means for holding said contact device in position with the resistance out of the armature-circuit.

In testimony whereof I afiix my signature in presence of two witnesses.

WILLIAM C. OBRIEN.

Witnesses:

JOHN J. CARROLL, HENRY H. MUELLER. 

